God computer is limping

Okay, forgive the presumptuous title, (and if this is in the wrong spot, new here) but I do seriously have an issue with a computer that really should not be struggling. I'm on the latest video drivers, latest bios, and I recently re-installed windows. I ran the benchmark for Bioshock Infinite on ultra DX11 and most of the FPS were 90-120, but sometimes it drops down to 29 and I can't figure out why. System info:

Case: NZXT Phantom 820  

Monitor: Dell U3011 2560x1600

Ram: G.Skill Ripjaws Z 64GB DDR3 @2400

PSU: Cooler Master Silent Pro Gold - 1200W

CPU: Intel i7-3970X EE 3.5GHz

Mobo: Asus Rampage IV E

HD: Samsung 840 Pro 512GB (RAID 0)

GPU: GTX 780 Ti (SLI X2)

Passmark was 4526 (if anyone actually uses PerformanceTest).

SLi? Maybe the game simply does not like it and occasionally just chunks frames every now and then. BioShock infinite is an AMD game anyway, not that it should matter, and Crossfire/SLi are generally problematic from time to time.

You should dig deeper; benchmark every viable component in your pc and compare results with advertised and/or regular stats (internet). You may or may not have a faulty or misconfigured piece of hardware.

I've never had to do serious bench marking before. Any idea on programs I should use?

Take a look to see if there is a later bios for your GPU's. The 780, ti's had issues with the early releases of bios's. Anything from crashing from overvolting to microstutter. It was fixed with the new bios. Take a look at the venders site to see if you can find a newer bios. Make sure its the right bios number before you flash.

Sorry to jack your thread but seeing as you have an 820 Phantom, Do you get random vibrations from the front panel when the HDD is in use? I cant seem to find the point on mine which is making the noise.

I'm assuming you mean motherboard bios (as far as I know that's the only bios, unless I'm an idiot...which is certainly likely). My bios is up to date for my mobo, got the latest ones of Asus. 

As to your issue I'm using solid state drives, so I don't have any vibration in my system. I did have an issue however with some of the fans not seated very well, ended up using liquid electrical tape on the threads and that eliminated my issues. Hope that helps somehow.

There are multipul bios's in a computer. Im talkin about the GPU bios. However if you have a PLX chip, flashing over that by mistake will kill the PLX chips bios which is seperate from the motherboard bios. But again, 780 ti's had problems with their bios. Flashing a newer one depending on the vender might solve your problem.